Hypothermia is defined as a temperature of <35C. It is a common presentation in the Emergency Departments esp in elderly population with ? Sepsis. Geriatric population is prone to suffer from hypothermia due to poor mobility and altered temperature perception in addition to the environmental factors. Let's look at the common causes of hypothermia:
Causes
- Environmental (often Accidental)
- Hypoglycaemia (hypothalamic dysfunction secondary to glucopenia)
- Hypothyroidism
- Hypopituitarism
- Hypoadrenalism
- Hypothalamic Dysfunction (Tumor, Stroke, Infarction)
- Sedatives and Alcohol
- Sepsis
- Massive Blood Transfusion
- Burns and Exfoliative Dermatitis
Systemic Effects
CVS - BP and CO rise initially but later there is a phase of CVS depression and a general slow down of metabolism. This may lead to hypotension which is exacerbated by concomitant hypovolumia. Hypothermia usually causes bradyarrythmiats such as slow AF, sinus bradycardia, J waves, AV blocks, QTc prolongation on EKG. The management should focus on rewarming rather than administering anti-arrythmics. Also, hypothermic myocardium is irritable, and ventricular fibrillation may be induced by rough handling of the patient.
RS - Decrease O2 utility and less CO2 production. Patients may show a respiratory alkalosis or acidosis due to CNS depression. Lactate may be elevated due to shivering and hypoxia. There is also depression of gag and cough reflex making aspiration likely. Hypothermia causes a leftward shift of the oxyhemoglobin dissociation curve and thus impairs oxygen release to tissues.
CNS - Confusion, lethargy, coma and unreactive pupils. There is decreased blood flow and cerebral protection against ischemic damages. Do not pronounce them dead until you are 100% sure. Use ECHO, ECG and Clinical judgment before you declare them dead.
Renal - Cold induced diuresis which contributes to volume loss, risk of rhabdo and AKI.
Haematological - Hemoconcentration, thrombotic and embolic complications, DIC and Hypothermia induced coagulopathy. This coagulopathy may not be evident of blood tests but seen clinically.
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